The bovine trophectoderm(TE) undergoes dramatic morphogenetic transitions and cell proliferation from the cavitating morula stage up to uterine endometrial attachment. Many studies have documented trophoblast specific gene expression profiles at various pre-attachment stages, yet genetic interactions within the transitioning TE gene regulatory network are not well characterized. Transcription factors OCT4 and CDX2 are co-expressed during early trophoblast elongation. In our study published in Molecular Reproduction & Development (2013), the bovine trophectoderm-derived CT-1 cell line was utilized as a genetic model to examine the roles of CDX2 and OCT4 within the bovine trophoblast gene regulatory network. TE-lineage transcription factors, CDX2, ERRB, ID2, SOX15, ELF5, HAND1, and ASCL2, were shown to be expressed in CT-1 cells. A nuclearlocalized, 360 amino acid OCT4 ortholog of the pluripotency-specific human OCT4A was also expressed. CDX2 and OCT4 levels were manipulated via overexpression and siRNA-mediated knockdown to delineate the roles of CDX2 and OCT4 within the CT-1 gene network,. An increase in CDX2 negatively regulated OCT4 expression, but increased expression of IFNT, HAND1, ASCL2, SOX15, and ELF5. A reduction of CDX2 levels exhibited a reciprocal effect, resulting in decreased expression of IFNT, HAND1, ASCL2, and SOX15. Both overexpression and knockdown of CDX2 increased ETS2 transcription. In contrast to CDX2, manipulation of OCT4 levels only revealed a positive autoregulatory mechanism and upregulation of ASCL2. Together, these results suggest that CDX2 is a core regulator of multiple trophoblast genes within CT-1 cells. (see Schiffmacher & Keefer (2013) Molecular Reproduction and Development. 80(10):826-839.)